Definition of libration in English:

libration

noun

Astronomy
  • An apparent or real oscillation of the moon, by which parts near the edge of the disc that are often not visible from the earth sometimes come into view.

    • ‘He discovered the libration of the Moon and this gained him fame which led to his appointment as professor of economics and mathematics at Göttingen in 1751.’
    • ‘The topic was on the libration of the Moon, that is the motion of the Moon which causes the face that it presents to the Earth to oscillate causing small changes in the position of the lunar features.’
    • ‘Its space segment will be composed of a group of X-ray telescopes based around one of the libration points or Lagrangian points.’
    • ‘Lagrange won the Académie des Sciences Prize in 1764 for a work on the libration of the Moon.’
    • ‘Permanent settlements have been proposed for the Moon and Mars, as well as stable positions in space equidistant from both Earth and Moon called the Lagrangian libration points.’

Origin

Early 17th century (denoting an oscillating motion, or equilibrium): from Latin libratio(n-), from the verb librare, from libra a balance.

Pronunciation:

libration

/lʌɪˈbreɪʃ(ə)n/